N-succinimide additives for azide imaging systems

ABSTRACT

Dry photoimaging processes and compositions employing 1,8diazidonaphthalene and certain N-substituted succinimide additives in a permeable film-forming plastic are disclosed.

United States Patent 1 1 1111 3,716,367

Ando 1 1 Feb. 13, 1973 1 4] N-SUCCINIMIDE ADDITIVES FOR 3,062,65011/1962 Sagura et a1. ..96/90 R AZIDE IMAGING SY T M 3,072,485 1/1963Reynolds et a1. ..96/91 N 3,092,494 6/1963 Sus et a1. ..96/91 N [751lnvemo" And", stamfori'conn- 3,282,693 11/1966 Sagura et a1. ..96 91 N3,287,128 11 1966 Lugasch ..96/91 N [73] Asslgnee' ga g: C Company3,519,425 7 1970 Marshall at 81.. ..96/91 N m or 3,598,586 8/1971 Gaspar..96 75 22 il May 1971 3,617,278 11/1971 HOlStBad et a1. ..96/90 R [21]Appl. No.: 147,111 OTHER PUBLICATIONS Dinaburg, M. S., PhotosensitiveDiazo Compounds, [52] US. Cl ..96/91 N, 96/49, 96/75, The Focal Press,1964, pp. 171-178.

96/90 R, 96/] 15 R Hoffman et 611,, .3. Chem. Soc. C., 1969, pp.769-772. 51 Int. Cl ..G03C 1/52,G03 1 72 f v V v p H [58] Field OfSearch ..96 91 N, Primary Examiner-Charles B r Jr.

90 R, 90 PC, 49.1 15 R, 115 P, 75, 88 Attorney-Robert Raymond 156116168115861186" 1 1 ABSTRACT Dry photoimaging processes and compositionsem- UNITED STATES PATENTS ploying 1,8-diazidonaphthalene and certainN-sub- 1,845,989 2 1932 Schmidt 6181 ..96/91 N Stituted succinimideadditives in a Permeable 2,692,826 10/1954 Neugebaueretal ....96 91 N frming plastic are disclosed.

3,042,515 7/1962 Wainer ..96/90 R 6 Claims, 1 Drawing Flgure o N0ADD/T/VE 1:1 5% was A------ 5% was /.5

VISUAL D/F F USE OPT/CAL DENSITY n STEP TABLET OPT/CAL DENSITYN-SUCCINIMIDE ADDITIVES FOR AZIDE IMAGING SYSTEMS This invention relatesto photosensitive compositions and processes for the formation of imageshaving broad spectra absorption characteristics and enhanced opticaldensities. More particularly, it relates to the use of variousN-substitute d succinimide additives in imaging systems employing1,8-diazidonaphthalene.

Photosensitive compounds, compositions and processes play an essentialrole in photography and the related arts dealing with the formation ofimages with the aid of some activating influence, such as light, heat,etc. For many applications, as in the case of printing on white paper,it is desirable to maximize the neutrality and optical density of theimage, in addition to achieving good color stability, speed, acuity,resolution and tonal range. it is also desirable to achieve theseadvantages by means of a convenient, dry imaging process employingrelatively inexpensive materials.

Accordingly, it is an object of the present invention to providephotosensitive compositions which are suitable for the formation ofimages having broad spectral absorption characteristics of the imagedspecies, high optical densities, as well as good image stability,acuity, resolution and tonal range. It is a further object to provide aconvenient, dry photoimaging process for the formation of such images.These and other objects and advantages of the present invention willbecome apparent from the description and examples which follow.

In accordance with the present invention, it has been unexpectedly foundthat the images produced by means of irradiating the photosensitivecompound, 1,8- diazidonaphthalene, can be substantially improved byemploying, in combination therewith, an N-substituted succinimide of thefollowing structure:

wherein X is a member of the group consisting of -Br, Cl and OH.

The additives of the present invention, namely, N- bromosuccinimide,N-chlorosuccinimide and N- hydroxysuccinimide are well known and can beobtained from a variety of commercial sources.

The photosensitive compositions of the present invention are prepared byuniformly distributing a photosensitive layer of polymer dope over thesurface of a conventional photographic substrate. The polymer dopecomprises a conventional, vapor permeable filmforming plastic havingincorporated (preferably as a solution) therein the photosensitivecompound, 1,8- diazidonaphthalene, and one or more of the abovesuccinimide additives. One or more conventional light sensitizers mayalso be employed to extend the sensitivity of the composition into therange of from 360 my. to 470 mg. or greater.

Suitable substrates include, for example, such materials as paper,plastic, wood, metal and glass.

Among the suitableconventional polymeric binders one may mention, forexample, polyvinyl chloride,

polyethylene, polymethylmethacrylate, polyvinyl acetate, celluloseacetate, copolymers of the corresponding monomers, and mixtures of theabove polymers and the like. Polyvinyl chloride is especially preferred.

Suitable commercially available film forming polymers include, forexample, the polyvinyl chloride polymers: Geon l0l, l0lXl3, E? by the B.F. Goodrich Company and Dow PVC-166 by the Dow Chemical Company;polyvinyl chloride-polyvinyl acetate copolymers: Geon 421 by the B. F.Goodrich Company; chlorinated polypropylene, Parlon P-lO by the HerculesPowder Company, polyvinyl acetate copolymers, Gelva C5, Vl6R by theMonsanto Company and the like.

The sensitized polymer dopes are prepared by forming a uniform solutionof the aromatic azide and the succinimide additive in the polymericbinder. This can be conveniently achieved through the use of an organicsolvent, such as, tetrahydrofuran or toluene, into which the polymericbinder, azido photosensitive compound, succinimide additive and otherdesired ingredients are dissolved. The resulting solution can be appliedto the photographic substrate by any conventional coating technique. Thesubstrate is then prepared for imaging by removing the solvent from thedope by evaporation.

In general, any conventional coating techniques employed in large andsmall scale coating operations may be employed in preparation of thephotosensitive systems. Of the suitable methods of applying thesensitized dope to the substrate, the Fixed Blade Method, the lmbibingMethod and the Meyer Rod Method are among the preferred techniques.

In the Fixed Blade Method, the base material is positioned under a fixedblade and an excess of the coating material is placed on the base. Thebase is then passed under the blade to produce a uniform coating havinga thickness determined by the distance between the mounted blade and thebase material.

In the lmbibing Method, a substrate having a plastic surface is coatedwith the active compound by passing it under a roller, touching asolution of the azido compound. The excess coating is removed from thesurface by an air knife. By way of illustration, one may mention passingpaper coated with polyvinyl chloride, polyvinyl acetate orpolymethylmethacrylate through a solution of 1,8-diazidonaphthalene andN-chlorosuccinimide in.

a solvent such as tetrahydrofuran, methyl ethyl ketone, acetone ortoluene or mixtures thereof.

In the Meyer Rod Method, the coating composition is placed at one end ofthe base material and a metal rod wound with fine wire is passed throughthe liquid causing it to be spread over the surface of the basematerial. The thickness of the coating produced by this method isdetermined by the size of the wire used in the winding.

The concentrations of azido compound and succinimide additiveadvantageously employed in the coating compositions and the thickness ofthe layer applied to the base may be varied to tailor the photosensitivesystem to achieve the desired degree of imaging speed, length of fixingperiod, image density, etc. Optimum concentrations and thicknesses will,of course, vary depending on the particular photosensitive compound andsuccinimide additive employed, the binder material and thickness of thebinder layer used, fixing time and temperature, among other factors. Ingeneral, satisfactory photoimages can be produced using bindercompositions having from about 1 percent to about 30 percent by weightof the azido compound and from about 0.1 percent to about percent byweight of the succinimide additive with coatings of from about 0.05 toabout 1.00 mils in thickness. Preferred concentrations of thesuccinimide based on the 1,8- diazidonaphthalene and thicknesses arefrom about percent to about 50 percent by weight and about 0.3 mils,respectively.

Generally, background colorup and diffusion time increase exponentiallywith film thickness. However, they are relatively unaffected byincreases in the concentration of the azido compounds.

The 1,8-diazidonaphthalene is sensitive to radiation containingwavelengths within the ultraviolet region. By means of the addition of asensitizing agent to the polymer binder, the sensitivity can be extendedinto the range of from 360 m to 470 mp. or greater. The energy transferof such systems is surprisingly efficient in view of the typically highviscosity of the binder polymer systems being sensitized.

Several advantages are provided by the use of sensitized systems. Theypermit the use of apparatus equipped with inexpensive and convenientlight sources, such as incandescent lamps, and allow projection printingthrough various optical systems with normal optical glass. They alsopermit the simultaneous use of both direct and indirect excitation ofazido compounds through simultaneous exposure of the photosensitivecompounds to both visible and vultraviolet absorbingsensitizer incombination with the azido composition.

Suitable sensitizers include, for example, fluoranthene, thioxanthrone,fluorenone, perylene, benzanthrone, benzophenone, phenazine andthioacridone.

Sensitizers which absorb light in the visible spectrum are of necessitycolored compounds. Where the colors caused thereby are found to beobjectionable, one may employ a volatile, film-permeable sensitizer,such as fluorenone, or benzanthrone. In each case, the sensitizer willdiffuse out of the binder composition during the fixing process.

Optimum relative concentrations of the sensitizer and azido compoundwill, of course, vary with the particular system being employed.Generally, energy transfer is favored by high concentrations of theazido compound. It is preferred to employ the sensitizer in a sufficientconcentration to completely absorb the incident light. However,excessively high concentrations of the sensitizer will cause completeabsorption of the incident light at the surface of the plastic matrixand may thereby reduce the efficiency of the system.

In the preparation of black and white images, it is generally desirableto maximize the optical density of the image produced. One means ofachieving this result is to increase the concentration of the 1,8-diazidonaphthalene employed as the photosensitive compound. Thisapproach, however, is limited by the solubility of the1,8-diazidonaphthalene in the polymer binder selected. Where thesolubility is exceeded, crystallization of the azide occurs in thephotosensitive composition. Such a result is highly undesirable due tothe fact that uniformity of composition is required for satisfactoryimage formation. In addition, the molecular nature of the imaging isdestroyed and one obtains grain as with conventional silver imagingprocesses.

It has unexpectedly been found that N-bromosuccinimide functions as acrystallization depressor, enabling the use of higher concentrations ofthe azido compound to achieve an enhanced optical density in the imagesproduced. In addition, this additive also functions to promote theformation of more neutral images than those produced in the absencethereof.

It is generally preferred to employ N-bromosuccinimide in concentrationsin the range of from about 1 percent to about 30 percent and 1,8-diazidonaphthalene in concentrations in the range of from about 0.1percent to about 20 percent.

N-chlorosuccinimide also functions to broaden the spectralcharacteristics of the images produced with l,8-diazidonaphthalene. Inaddition, this additive unexpectedly permits the'formation of images ofenchanced contrast by substantially increasing the optical density ofthe exposed areas while producing only small increases in the opticaldensity of the background, as seen, for example, in the attached FIGURE.It is generally preferred to employ this additive in the concentrationranges indicated above for the bromo analog.

The N-hydroxysuccinimide additive functions to greatly enhance theoptical density of the images produced with 1,8-diazidonaphthalene andto broaden the spectral characteristics of the images producedtherewith. In the practice of the present invention, it is generallypreferred to employ this additive in the concentration ranges specifiedfor the bromo analog above.

A convenient source of ultraviolet radiation is provided by lamps whichemit a wide range of ultraviolet frequencies. A light table equippedwith a film transparency (positive or negative) and a bank ofultraviolet-rich fluorescent lamps, such as, 15 Watt Black Light, No.F15T8-BL by General Electric and Rayonet Photochemical Reactor Lamps,No. RPR 3000A by The Southern New England Ultraviolet Company provides aconvenient source of activating radiation. Conventional azo printingmachines, equipped with high pressure mercury vapor lamps may also beemployed. Since they emit both visible and ultraviolet light, they areespecially well adapted for use with those compositions havingsensitizers to visible light.

Absorption of incident light can be maximized by matching thefrequencies of the incident light with the absorption frequencies of thearomatic azido compound or the sensitizer.

Patterning of the activating radiation can generally be achieved by anyof the conventional methods. Suitable methods include passing the lightthrough a film transparency or a template, use of a cathode ray tubecontaining an ultraviolet phosphor, such as, a Litton lndustries'Cathode Ray Tube, Serial No. 4188, which contains a PM) phosphor; andusing an ultraviolet pen light, such as Ultraviolet Products, Inc.Pen-Light, or ultraviolet laser, such as might be used in spatialfrequency modulation and holographic information storage, etc.

Optimum periods of irradiation will vary widely, depending upon theparticular photosensitive composition, opacity of transparency, andlight source employed. Exposure for a few seconds in a conventionaldiazo printer is generally adequate while periods of two minutes or moremay be required for a source such as the abovementioned light table.

In the formation of images from 1,8- diazidonaphthalene in combinationwith one or more of the above N-substituted succinimide additives, it isgenerally preferred to fix the neutral image produced by heat. This isconveniently achieved by heating the exposed substrate to a temperaturesufficient to volatilize the unreacted azido compound from the polymericbinder. The optimum temperature and heating period will vary with theparticular system employed and the heating means used. In the case ofpolyvinyl chloride binders, this can generally be achieved by heatingthe exposed composition at 135 C. for a period of from about 1 to about5 minutes or less.

Thermal fixing of the images can be achieved by merely placing theexposed film or paper into an oven. However, any other conventionalmeans of heating the substrate may be suitably employed. For example,the fixing process may be automated by providing a means for passing thephotosensitive substrate through an area in which exposure takes placeinto a fixing area where it is heated, for example, by passing it underheating lamps or over a heated platen. Passage of a hot stream of airover the film surface is also advantageously em ployed. In addition toheating the upper surface of the exposed film or paper, volatilizationof the unreacted azido compound from the background is therebyfacilitated, greatly reducing the fixing time required.

The processes and compositions of the present invention are furtherillustrated by the following examples which are not to be taken aslimitative thereof. In each case, the parts and percentages specifiedtherein are by weight unless otherwise indicated.

EXAMPLE 1 Crystallization Suppression The unique ability ofN-bromosuccinimide to inhibit crystallization of 1,8-diazidonaphthalenein photosensitive compositions is demonstrated by the following tests inwhich various additives were incorporated with the azido compound into apolyvinyl chloride copolymer (Geon 421 by B. F. Goodrich Co.). In eachcase, 0.03 g. of the azide were combined with 0.012 to about 0.024 gramsof the additive. The resultant mixture was added to about 0.07 grams ofthe polymer and the resulting mixture was dissolved in 0.72 grams oftetrahydrofuran. The solution was applied as a uniform coating to a 3mil polyester film (Celanar by the Celanese Corp.). The coating wasachieved by means of a Gardner Automatic Mechanical Applicator equippedwith a Gardner Knife. Prior to use, the coated films were air-dried atroom temperature to permit the solvent evaporation.

The dried films were exposed to image light by means of a LogEtronicsInc. imaging device equipped with 12 black light/blue (F8T5/BLB), G. E.fluorescent lights with a total black light intensity of about 4 mw/cmat the film plane. After imaging, the exposed TABLE I Crystallization ofDAN Additive Tested None- N-Bromosuccinimide N-ChlorosuccinimideN-I-Iydroxysuccinimide Succinirnide Suecinic Acid Succinic AnhydrideDichloromaleic Anhydride l-Chloro-2,4-Dinitrobenzene Ethyl PhthalateCyclohexyl Amine Ethylene Glycol Santicizer B-l6 Paraplex G-GO' StearicAcid Polyethylene Glycol Benzoic Acid Salicilic Acid p-ChloroamineTexaphor l ,4-Dinitronaphthalene Fluoranthene 2,3DimethylnaphthaleneZ-Methoxynaphthalene Maleic Acid a purple Image Color Pd BB BB Fcommercial plasticizer by Rohm and Haas Co.

b blue-black g commercial anti-settling agent by Standard Chemical Co.

c crystallized d uncrystallized e commercial plasticizer by MonsantoChemical Co.

EXAMPLE 2 In order to quantitatively evaluate the relative contrastachieved in 1,8-diazidonaphthalene imaging systems having image colormodification by addition of N-chlorosuccinimide or N-bromosuccinimide,the following tests were performed.

Three photosensitive compositions were prepared using 3 mil films ofpolyester for support (Celanar by the Celanese Corporation of America).A control sample was prepared by coating the support film with a 0.4 millayer of a polyvinyl chloride-polyvinyl acetate copolymer (Geon 421, bythe B. F. Goodrich Company) containing 15 percent by weight of thephotosensitive compound, 1,8diazidonaphthalene. The coating compositionwas prepared by dissolving the polymer and photosensitive compound intetrahydrofuran. The resulting solution was applied to the filmsubstrate using the Gardner Knife coating technique. Prior to use, thesolvent was permitted to evaporate from the binder composition.

Two test photosensitive compositions were prepared as in the case of thecontrol composition above with the exception that the coatings were made5 percent in N- bromosuccinimide and 5 percent in N-chlorosuccinimide,respectively.

The three test compositions were imaged by exposure to a LogEtronicslnc. imaging device equipped with 12 black light/blue fluorescent bulbs(FSTSIBLB by the General Electric Company) through a No. 1A EastmanKodak, 10-step Densitometric Tablet for about 5 minutes.

The imaged systems were fixed by heating in a circulating air ovencontrolled at 135 C. for a period of about minutes. The developed andfixed image densities were measured by means of a Macbeth TD-102Densitometer Tablet. The relative contrasts of the images produced weredetermined quantitatively by preparing DlogE curves and determininggamma, 7, defined as the maximum slope of the DlogE curves as projectedon the logE axis. The data obtained for each system is graphicallydepicted in the attached figure. The image colors produced and thegammas observed are set forth in Table 11 below.

" TABLE ll Additive image Color 'y No Additive Q Purple Purple-Black1.41 5% NCS El Deep Blue Gray-Black 1.72 5% NBS A Deep Blue Gray-Black1.32

It is apparent from the results obtained, that the images prepared fromthe imaging systems employing N-bromosuc-cinimide andN-chlorosuccinimide are of substantially greater neutrality than thoseachieved in their absence. It is further evident that the N-chlorosuccinimide system unexpectedly provides additional advantages byway of contrast. This additive permits the achievement of substantiallyenhanced optical densities without substantial impairment of thebackground optical densities; a combination of spectral andDensitometric characteristics which permit the preparation ofphotographs having a wide range. of variation in tone with a completelyneutral image in addition to the preparation of high quality, sharplined images, without substantially darkening the image background.While such properties are especially useful in the preparation of blackand white photographs on paper, they are also of great importance inpreparing microfilms for the projection of high contrast straight lineand continuous tone images.

EXAMPLE 3 The effect of N-hydroxysuccinimide on the images produced in1,8-diazidonaphthalene photosensitive systems is demonstrated in thefollowing tests.

The photosensitive compositions were prepared by the general procedureof Example 2 using a film .coating prepared by dissolving 0.1 gram ofN-hydroxysuccinimide, 0.17 gram of 1,8-diazidonaphtahlene and 0.98 gramof polyvinyl chloride copolymer (Geon 421 by the B. F. Goodrich Company)in 8.85 grams of methyl ethyl ketone. Coatings 0.3 mil in thickness wereprepared on 3 mil films of polyester (Celanar). The coated films wereimaged by exposure in the previously mentioned LogEtronics lnc. U.V.light unit for 3 minutes and heat fixed for 2 minutes at 135 C. Aphotopic density of 0.74 was observed in a control sample prepared asabove without the addition of N- hydroxysuc-cinimide; while, photopicdensities of 1.26 were achieved in the test samples employingN-hydroxysuccmlml fi The comparative photopic density of imagespreparedwith photosensitive compositions containing 30 percent concentrations ofl,8diazidonaphthalene with N-chlorosuccinimide and N-bromo-succinimideadditives is demonstrated by the following tests.

Photosensitive compositions were prepared by the general procedure ofExample 3 above, using 0.36 gram of 1,8-diazidonaphthalene, 0.85 gram offilmforming polymer (Geon 421), 7.65 grams of methyl ethyl ketone, 1.13grams of tetrahydrofuran and 0.12 gram of the N-substituted succinimideto be tested. The compositions produced were in each case imaged by theprocedure of Example 3 and fixed by heating at C. for 3 minutes. Theresulting image color and comparative photopic densities of the imagesproduced are set forth in Table 11] below.

TABLE 111 Additive Image Color O.D. No Additive Purple 0.46 NCSBlue'Black 0.97 NBS Blue-Black 0.87

It can be seen that in each case a substantial enchancement in opticaldensity (O.D.) was achieved through the use of the N-substitutedsuccinimide additive in addition to a substantial enhancement in imagecolor neutrality.

lclaimzl. A photosensitive element suitable for the formation of imagescomprising a photographic substrate having a coating deposited thereon,said coating comprising a vapor permeable, film-forming plastic having1,8-diazidonaphthalene and a compound of the following formula uniformlydissolved therein:

NI fi" wherein X is a member of the group consisting of Br, Cl and -OH.

2. A element according to claim 1 wherein the plastic is selected fromthe group consisting of polyvinyl chloride, polyvinyl acetate and vinylchloride-vinyl acetate copolymers.

3. A element according to claim 2 wherein the coating contains aconcentration of 1,8-diazidonaphthalene in the range of from about 1percent to about 30'percent by weight and contains a concentration ofthe succinimide in the range of from about 0.1 percent to about 20percent by weight and said coating has a thickness of from about 0.05 toabout 1.00 mils.

4. A element according to claim 3 wherein the succinimide isN-chlorosuccinimide.

5. A element according to claim 1 wherein said coating further containsa visible or ultraviolet light sen-- I

1. A photosensitive element suitable for the formation of imagescomprising a photographic substrate having a coating deposited thereon,said coating comprising a vapor permeable, film-forming plastic having1,8-diazidonaphthalene and a compound of the following formula uniformlydissolved therein: wherein X is a member of the group consisting of -Br,-Cl and -OH.
 2. A element according to claim 1 wherein the plastic isselected from the group consisting of polyvinyl chloride, polyvinylacetate and vinyl chloride-vinyl acetate copolymers.
 3. A elementaccording to claim 2 wherein the coating contains a concentration of1,8-diazidonaphthalene in the range of from about 1 percent to about 30percent by weight and contains a concentration of the succinimide in therange of from about 0.1 percent to about 20 percent by weight and saidcoating has a thickness of from about 0.05 to about 1.00 mils.
 4. Aelement according to claim 3 wherein the succinimide isN-chlorosuccinimide.
 5. A element according to claim 1 wherein saidcoating further contains a visible or ultraviolet light sensitizerdissolved therein.